The present invention relates to improved fluid strainers and to such strainers which facilitate conversion thereof between manual and automatic modes of operation.
Industrial strainer devices are well-known in the art for use in removing solid debris from in-line fluid flow conditions. One common type of industrial strainer is a so-called basket type which is physically disposed in a fluid line which supplies raw water to a fluid apparatus, such as a fire main pipeline. However, basket type strainers require the basket and the contents thereof to be removed. Such removal requires several hours of cleaning and labor time. Just as significantly the fluid system employing the basket strainer is down. Such down time presents, of course, added significant commercial drawbacks.
A significant improvement over such approaches is a fluid strainer apparatus, such as the type described in U.S. Pat. No. 3,278,038. These strainers are constructed and operated so as to be in-line and facilitate removal of solid particles in liquids flowing through pipelines by straining and subsequently scraping and flushing functions aimed at removing debris build-up on the strainer. Specifically, these strainers employ a peripheral in-flow strainer or screen, whereby solids are collected on an exterior surface of a perforated rotatable screen. A stationary scraper blade is positioned adjacent the rotatable screen so as to remove solid build-up from the exterior screen surface when the latter is rotated. For effecting cleaning, such screens are manually rotated or are driven by a motor. Some of the fluid strainers have collecting sump areas which hold the solids removed from the screen for subsequent removal from a waste discharge port during a sump flushing operation.
While the foregoing fluid strainer provides significant advantages, there is nevertheless a desire to improve upon their performances. For instance, the scraper blades when installed have pre-set clearances between the blades' scraping edge and the exterior surface of the rotating screen. Heretofore however, there was not a way of determining whether the predetermined clearances existed in fact. In addition, these fluid strainers have not been provided with any approach for allowing inspection and adjustment of the scraping blade's clearance, as well as allowing removal of objects which are difficult to scrape, such as leaves and the like.
Furthermore, many of the fluid strainers which are motorized have a motor driven worm gear arrangement which is coupled to the strainer's screen drive shaft by an external spur gear arrangement. The spur gear and the strainer screen drive shaft extend from the strainer's housing and are protected by a cage. The cage however does not entirely enclose the gear train system. Because of this construction, the gear train is bulky and many of the components are exposed to corrosive environmental factors and some of the rotating gears are exposed to the extent that they present potential safety concerns to operators.
Moreover, it is commercially desireable to provide a strainer apparatus which is easily convertible from a manual mode of operation to a motorized mode of operation. Successful approaches exist for achieving such conversion, such as the approach utilized with the HELLAN.RTM. fluid strainers that which are available from Cleveland Gear, Cleveland, Ohio, USA. These last noted type strainers achieve conversion by removal from the strainer of an entire manual handwheel assembly which includes not only the handwheel; but the handwheel's journal housing, hand wheel drive shaft, as well as rotatable screen and replacing them by a motorized drive system which includes a rotatable screen, a screen drive shaft, and a shaft journal housing. While successful approaches exist for conversion nevertheless there exists a desire to improve upon them.